mudbox is pretty much the only free (student) program that can do this well. I'm sure you can do the same thing in Zbrush, Blender, sculptris and so on, but that would require a whole lot more effort especially concidering nblx already mapped it as a .mud file. I think you are better off just trying to fix the error. You can convert the .mud file to .obj and export it to a different program, make a script that exports all the layers as individual files and import them in to toribash, but that sounds stressful.
Last edited by Ezeth; Mar 26, 2016 at 10:56 PM.